1. Field of the Invention
This invention relates generally to pipe construction machines for constructing sheet metal tubes or pipes for many purposes, as for example, heating and ventillating conduits. The invention is particularly concerned with a method and machine for assembling a preformed pipe blank into a finished pipe without any deforming of the sheet metal material.
2. Description of the Prior Art
It is known in the pipe fabricating art to provide machines for forming a finished tube or pipe from sheet metal material. Examples of such prior art machines are shown in U.S. Pat. Nos. 766,531, 854,136, 1,428,427, 1,681,880 and 2,845,889. The aforementioned prior art pipe making machines are all directed to form a finished or complete pipe by carrying out a final deforming operation of some sort to secure the edges of the sheet metal material together. A disadvantage of such prior art pipe making machines is that the final pipe or product made by such machines must be shipped in the finished tubular form which takes up more shipping volume than if the pipes could be shipped in blank form and in a stacked arrangement, and then assembled at the point of use.
U.S. Pat. Nos. 3,154,037 and 3,208,140 disclose a method and apparatus for anchoring the seams of lock seam tubing together. However, the machines shown and used in said patents deforms the lock seam material, and it does not merely assemble the ends of a pipe blank together without any deforming of the material. Further examples of prior art pipe jointing apparatuses which form pipe by deforming the sheet material are shown in U.S. Pat. Nos. 628,643 and 2,278,155.